org.apache.flink.api.java.functions.KeySelector Java Examples

public static <X, K> KeySelector<X, K> getSelectorForOneKey(
		Keys<X> keys, Partitioner<K> partitioner, TypeInformation<X> typeInfo, ExecutionConfig executionConfig) {
	if (!(typeInfo instanceof CompositeType)) {
		throw new InvalidTypesException(
				"This key operation requires a composite type such as Tuples, POJOs, case classes, etc");
	}
	if (partitioner != null) {
		keys.validateCustomPartitioner(partitioner, null);
	}

	CompositeType<X> compositeType = (CompositeType<X>) typeInfo;
	int[] logicalKeyPositions = keys.computeLogicalKeyPositions();
	if (logicalKeyPositions.length != 1) {
		throw new IllegalArgumentException("There must be exactly 1 key specified");
	}

	TypeComparator<X> comparator = compositeType.createComparator(
			logicalKeyPositions, new boolean[] { true }, 0, executionConfig);
	return new OneKeySelector<>(comparator);
}
 

@Test(expected = InvalidProgramException.class)
public void testJoinKeyMixing3() {

	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<Tuple5<Integer, Long, String, Long, Integer>> ds1 = env.fromCollection(emptyTupleData, tupleTypeInfo);
	DataSet<CustomType> ds2 = env.fromCollection(customTypeData);

	// should not work, incompatible types
	ds1.join(ds2)
	.where(2)
	.equalTo(
			new KeySelector<CustomType, Long>() {

					@Override
					public Long getKey(CustomType value) {
						return value.myLong;
					}
				}
			);
}
 

public static DataStream subscribe(DataStream<SamoaType> stream, PartitioningScheme partitioning) {
	switch (partitioning) {
		case BROADCAST:
			return stream.broadcast();
		case GROUP_BY_KEY:
			return stream.keyBy(new KeySelector<SamoaType, String>() {
				@Override
				public String getKey(SamoaType samoaType) throws Exception {
					return samoaType.f0;
				}
			});
		case SHUFFLE:
		default:
			return stream.shuffle();
	}
}
 

@Test
public void testSortPartitionWithKeySelector4() {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<Tuple4<Integer, Long, CustomType, Long[]>> tupleDs = env.fromCollection(tupleWithCustomData, tupleWithCustomInfo);

	// should work
	try {
		tupleDs.sortPartition(new KeySelector<Tuple4<Integer, Long, CustomType, Long[]>, Tuple2<Integer, Long>>() {
			@Override
			public Tuple2<Integer, Long> getKey(Tuple4<Integer, Long, CustomType, Long[]> value) throws Exception {
				return new Tuple2<>(value.f0, value.f1);
			}
		}, Order.ASCENDING);
	} catch (Exception e) {
		Assert.fail();
	}
}
 

@Test
public void testJoinKeyMixedKeySelectorTurned() {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<CustomType> ds1 = env.fromCollection(customTypeData);
	DataSet<CustomType> ds2 = env.fromCollection(customTypeData);
	try {
		ds1.join(ds2).where(new KeySelector<CustomType, Integer>() {
			@Override
			public Integer getKey(CustomType value) throws Exception {
				return value.myInt;
			}
		}).equalTo("myInt");
	} catch (Exception e) {
		e.printStackTrace();
		Assert.fail();
	}
}
 

@Test
public void testRangePartitionCustomPartitionerByKeySelector() throws Exception {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

	final DataSet<CustomPojo> ds = getPojoDataSet(env);
	ds.partitionCustom(new Partitioner<Integer>() {
		@Override
		public int partition(Integer key, int numPartitions) {
			return 1;
		}
	}, new KeySelector<CustomPojo, Integer>() {
		@Override
		public Integer getKey(CustomPojo value) throws Exception {
			return value.getNumber();
		}
	});
}
 

@Test
public void testCoGroupKeyMixing2() {

	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<Tuple5<Integer, Long, String, Long, Integer>> ds1 = env.fromCollection(emptyTupleData, tupleTypeInfo);
	DataSet<CustomType> ds2 = env.fromCollection(customTypeData);

	// should work
	try {
		ds1.coGroup(ds2)
		.where(3)
		.equalTo(
				new KeySelector<CustomType, Long>() {

						@Override
						public Long getKey(CustomType value) {
							return value.myLong;
						}
					}
				);
	} catch (Exception e) {
		Assert.fail();
	}
}
 

@Test
@SuppressWarnings("serial")
public void testGroupByKeySelector3() {

	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	this.customTypeData.add(new CustomType());

	try {
		DataSet<CustomType> customDs = env.fromCollection(customTypeData);
		// should not work
		customDs.groupBy(
				new KeySelector<GroupingTest.CustomType, CustomType>() {
					@Override
					public CustomType getKey(CustomType value) {
						return value;
					}
				});
	} catch (Exception e) {
		Assert.fail();
	}
}
 

@Test
public void testSortPartitionWithKeySelector4() {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<Tuple4<Integer, Long, CustomType, Long[]>> tupleDs = env.fromCollection(tupleWithCustomData, tupleWithCustomInfo);

	// should work
	try {
		tupleDs.sortPartition(new KeySelector<Tuple4<Integer, Long, CustomType, Long[]>, Tuple2<Integer, Long>>() {
			@Override
			public Tuple2<Integer, Long> getKey(Tuple4<Integer, Long, CustomType, Long[]> value) throws Exception {
				return new Tuple2<>(value.f0, value.f1);
			}
		}, Order.ASCENDING);
	} catch (Exception e) {
		Assert.fail();
	}
}
 

@Test(expected = InvalidProgramException.class)
public void testJoinKeyMixing4() {

	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<Tuple5<Integer, Long, String, Long, Integer>> ds1 = env.fromCollection(emptyTupleData, tupleTypeInfo);
	DataSet<CustomType> ds2 = env.fromCollection(customTypeData);

	// should not work, more than one key field position
	ds1.join(ds2)
	.where(1, 3)
	.equalTo(
			new KeySelector<CustomType, Long>() {

					@Override
					public Long getKey(CustomType value) {
						return value.myLong;
					}
				}
			);
}
 

@Test
public void testSortPartitionWithKeySelector1() throws Exception {
	/*
	 * Test sort partition on an extracted key
	 */

	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	env.setParallelism(4);

	DataSet<Tuple3<Integer, Long, String>> ds = CollectionDataSets.get3TupleDataSet(env);
	List<Tuple1<Boolean>> result = ds
		.map(new IdMapper<Tuple3<Integer, Long, String>>()).setParallelism(4) // parallelize input
		.sortPartition(new KeySelector<Tuple3<Integer, Long, String>, Long>() {
			@Override
			public Long getKey(Tuple3<Integer, Long, String> value) throws Exception {
				return value.f1;
			}
		}, Order.ASCENDING)
		.mapPartition(new OrderCheckMapper<>(new Tuple3AscendingChecker()))
		.distinct().collect();

	String expected = "(true)\n";

	compareResultAsText(result, expected);
}
 

@Test
public void testRangePartitionerOnSequenceData() throws Exception {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSource<Long> dataSource = env.generateSequence(0, 10000);
	KeySelector<Long, Long> keyExtractor = new ObjectSelfKeySelector();

	MapPartitionFunction<Long, Tuple2<Long, Long>> minMaxSelector = new MinMaxSelector<>(new LongComparator(true));

	Comparator<Tuple2<Long, Long>> tuple2Comparator = new Tuple2Comparator(new LongComparator(true));

	List<Tuple2<Long, Long>> collected = dataSource.partitionByRange(keyExtractor).mapPartition(minMaxSelector).collect();
	Collections.sort(collected, tuple2Comparator);

	long previousMax = -1;
	for (Tuple2<Long, Long> tuple2 : collected) {
		if (previousMax == -1) {
			previousMax = tuple2.f1;
		} else {
			long currentMin = tuple2.f0;
			assertTrue(tuple2.f0 < tuple2.f1);
			assertEquals(previousMax + 1, currentMin);
			previousMax = tuple2.f1;
		}
	}
}
 

private static <TWarningType extends IWarning> DataStream<TWarningType> toWarningStream(DataStream<LocalWeatherData> localWeatherDataDataStream, IWarningPattern<LocalWeatherData, TWarningType> warningPattern) {
    PatternStream<LocalWeatherData> tempPatternStream = CEP.pattern(
            localWeatherDataDataStream.keyBy(new KeySelector<LocalWeatherData, String>() {
                @Override
                public String getKey(LocalWeatherData localWeatherData) throws Exception {
                    return localWeatherData.getStation().getWban();
                }
            }),
            warningPattern.getEventPattern());

    DataStream<TWarningType> warnings = tempPatternStream.select(new PatternSelectFunction<LocalWeatherData, TWarningType>() {
        @Override
        public TWarningType select(Map<String, List<LocalWeatherData>> map) throws Exception {
            return warningPattern.create(map);
        }
    }, new GenericTypeInfo<TWarningType>(warningPattern.getWarningTargetType()));

    return warnings;
}
 

@Test
public void testProcessWindowState() throws Exception {
	final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
	env.setStreamTimeCharacteristic(TimeCharacteristic.IngestionTime);
	env.registerTypeWithKryoSerializer(File.class, JavaSerializer.class);

	DataStream<File> src = env.fromElements(new File("/"));

	SingleOutputStreamOperator<?> result = src
			.keyBy(new KeySelector<File, String>() {
				@Override
				public String getKey(File value) {
					return null;
				}
			})
			.timeWindow(Time.milliseconds(1000))
			.process(new ProcessWindowFunction<File, String, String, TimeWindow>() {
				@Override
				public void process(String s, Context ctx,
						Iterable<File> input, Collector<String> out) {}
			});

	validateListStateDescriptorConfigured(result);
}
 

@Test
public void testRangePartitionerOnSequenceData() throws Exception {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSource<Long> dataSource = env.generateSequence(0, 10000);
	KeySelector<Long, Long> keyExtractor = new ObjectSelfKeySelector();

	MapPartitionFunction<Long, Tuple2<Long, Long>> minMaxSelector = new MinMaxSelector<>(new LongComparator(true));

	Comparator<Tuple2<Long, Long>> tuple2Comparator = new Tuple2Comparator(new LongComparator(true));

	List<Tuple2<Long, Long>> collected = dataSource.partitionByRange(keyExtractor).mapPartition(minMaxSelector).collect();
	Collections.sort(collected, tuple2Comparator);

	long previousMax = -1;
	for (Tuple2<Long, Long> tuple2 : collected) {
		if (previousMax == -1) {
			previousMax = tuple2.f1;
		} else {
			long currentMin = tuple2.f0;
			assertTrue(tuple2.f0 < tuple2.f1);
			assertEquals(previousMax + 1, currentMin);
			previousMax = tuple2.f1;
		}
	}
}
 

public KeyedTwoInputStreamOperatorTestHarness(
		TwoInputStreamOperator<IN1, IN2, OUT> operator,
		KeySelector<IN1, K> keySelector1,
		KeySelector<IN2, K> keySelector2,
		TypeInformation<K> keyType,
		int maxParallelism,
		int numSubtasks,
		int subtaskIndex) throws Exception {
	super(operator, maxParallelism, numSubtasks, subtaskIndex);

	ClosureCleaner.clean(keySelector1, ExecutionConfig.ClosureCleanerLevel.RECURSIVE, false);
	ClosureCleaner.clean(keySelector2, ExecutionConfig.ClosureCleanerLevel.RECURSIVE, false);
	config.setStatePartitioner(0, keySelector1);
	config.setStatePartitioner(1, keySelector2);
	config.setStateKeySerializer(keyType.createSerializer(executionConfig));
}
 

/**
 * Creates a new {@code WindowOperator} based on the given policies and user functions.
 */
public WindowOperator(
		WindowAssigner<? super IN, W> windowAssigner,
		TypeSerializer<W> windowSerializer,
		KeySelector<IN, K> keySelector,
		TypeSerializer<K> keySerializer,
		StateDescriptor<? extends AppendingState<IN, ACC>, ?> windowStateDescriptor,
		InternalWindowFunction<ACC, OUT, K, W> windowFunction,
		Trigger<? super IN, ? super W> trigger,
		long allowedLateness,
		OutputTag<IN> lateDataOutputTag) {

	super(windowFunction);

	checkArgument(!(windowAssigner instanceof BaseAlignedWindowAssigner),
		"The " + windowAssigner.getClass().getSimpleName() + " cannot be used with a WindowOperator. " +
			"This assigner is only used with the AccumulatingProcessingTimeWindowOperator and " +
			"the AggregatingProcessingTimeWindowOperator");

	checkArgument(allowedLateness >= 0);

	checkArgument(windowStateDescriptor == null || windowStateDescriptor.isSerializerInitialized(),
			"window state serializer is not properly initialized");

	this.windowAssigner = checkNotNull(windowAssigner);
	this.windowSerializer = checkNotNull(windowSerializer);
	this.keySelector = checkNotNull(keySelector);
	this.keySerializer = checkNotNull(keySerializer);
	this.windowStateDescriptor = windowStateDescriptor;
	this.trigger = checkNotNull(trigger);
	this.allowedLateness = allowedLateness;
	this.lateDataOutputTag = lateDataOutputTag;

	setChainingStrategy(ChainingStrategy.ALWAYS);
}
 

@Test
public void testRangePartitionBySelectorComplexKeyWithOrders() throws Exception {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

	final DataSet<NestedPojo> ds = getNestedPojoDataSet(env);
	ds.partitionByRange(new KeySelector<NestedPojo, CustomPojo>() {
		@Override
		public CustomPojo getKey(NestedPojo value) throws Exception {
			return value.getNested();
		}
	}).withOrders(Order.ASCENDING);
}
 

@Test(expected = InvalidProgramException.class)
public void testJoinKeyMixedWrong() {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<CustomType> ds1 = env.fromCollection(customTypeData);
	DataSet<CustomType> ds2 = env.fromCollection(customTypeData);
	// wrongly mix String and Integer
	ds1.join(ds2).where("myString").equalTo(new KeySelector<CustomType, Integer>() {
		@Override
		public Integer getKey(CustomType value) throws Exception {
			return value.myInt;
		}
	});
}
 

@Test
public void testStreamConfig() {
	ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSource<String> input = env.fromElements("");

	BootstrapTransformation<String> transformation = OperatorTransformation
		.bootstrapWith(input)
		.keyBy(new CustomKeySelector())
		.transform(new ExampleKeyedStateBootstrapFunction());

	StreamConfig config = transformation.getConfig(OperatorIDGenerator.fromUid("uid"), new MemoryStateBackend(), null);
	KeySelector selector = config.getStatePartitioner(0, Thread.currentThread().getContextClassLoader());

	Assert.assertEquals("Incorrect key selector forwarded to stream operator", CustomKeySelector.class, selector.getClass());
}
 

@Test
public void testGroupedReduce() throws Exception {

	KeySelector<Integer, Integer> keySelector = new IntegerKeySelector();

	StreamGroupedReduce<Integer> operator = new StreamGroupedReduce<>(new MyReducer(), IntSerializer.INSTANCE);

	OneInputStreamOperatorTestHarness<Integer, Integer> testHarness =
			new KeyedOneInputStreamOperatorTestHarness<>(operator, keySelector, BasicTypeInfo.INT_TYPE_INFO);

	long initialTime = 0L;
	ConcurrentLinkedQueue<Object> expectedOutput = new ConcurrentLinkedQueue<>();

	testHarness.open();

	testHarness.processElement(new StreamRecord<>(1, initialTime + 1));
	testHarness.processElement(new StreamRecord<>(1, initialTime + 2));
	testHarness.processWatermark(new Watermark(initialTime + 2));
	testHarness.processElement(new StreamRecord<>(2, initialTime + 3));
	testHarness.processElement(new StreamRecord<>(2, initialTime + 4));
	testHarness.processElement(new StreamRecord<>(3, initialTime + 5));

	expectedOutput.add(new StreamRecord<>(1, initialTime + 1));
	expectedOutput.add(new StreamRecord<>(2, initialTime + 2));
	expectedOutput.add(new Watermark(initialTime + 2));
	expectedOutput.add(new StreamRecord<>(2, initialTime + 3));
	expectedOutput.add(new StreamRecord<>(4, initialTime + 4));
	expectedOutput.add(new StreamRecord<>(3, initialTime + 5));

	TestHarnessUtil.assertOutputEquals("Output was not correct.", expectedOutput, testHarness.getOutput());
}
 

public static <T> OneInputStreamOperatorTestHarness<Event, T> getCepTestHarness(
	CepOperator<Event, Integer, T> cepOperator) throws Exception {
	KeySelector<Event, Integer> keySelector = new TestKeySelector();

	return new KeyedOneInputStreamOperatorTestHarness<>(
		cepOperator,
		keySelector,
		BasicTypeInfo.INT_TYPE_INFO);
}
 

@Test
@SuppressWarnings("rawtypes")
public void testMergingWindowsWithEvictor() throws Exception {
	StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
	env.setStreamTimeCharacteristic(TimeCharacteristic.IngestionTime);

	DataStream<Integer> source = env.fromElements(1, 2);

	DataStream<String> window1 = source
			.keyBy(new KeySelector<Integer, String>() {
				@Override
				public String getKey(Integer value) throws Exception {
					return value.toString();
				}
			})
			.window(EventTimeSessionWindows.withGap(Time.seconds(5)))
			.evictor(CountEvictor.of(5))
			.process(new TestProcessWindowFunction());

	final OneInputTransformation<Integer, String> transform = (OneInputTransformation<Integer, String>) window1.getTransformation();
	final OneInputStreamOperator<Integer, String> operator = transform.getOperator();
	Assert.assertTrue(operator instanceof WindowOperator);
	WindowOperator<String, Integer, ?, ?, ?> winOperator = (WindowOperator<String, Integer, ?, ?, ?>) operator;
	Assert.assertTrue(winOperator.getTrigger() instanceof EventTimeTrigger);
	Assert.assertTrue(winOperator.getWindowAssigner() instanceof EventTimeSessionWindows);
	Assert.assertTrue(winOperator.getStateDescriptor() instanceof ListStateDescriptor);

	processElementAndEnsureOutput(winOperator, winOperator.getKeySelector(), BasicTypeInfo.STRING_TYPE_INFO,  1);
}
 

private KeyedOneInputStreamOperatorTestHarness<String, String, Integer> getHarnessTest(
	KeySelector<String, String> keySelector,
	int maxParallelism,
	int taskParallelism,
	int subtaskIdx) throws Exception {
	return new KeyedOneInputStreamOperatorTestHarness<>(
		new KeyedProcessOperator<>(new TestKeyedFunction()),
		keySelector,
		BasicTypeInfo.STRING_TYPE_INFO,
		maxParallelism,
		taskParallelism,
		subtaskIdx);
}
 

private static JobGraph createJobGraphWithKeyedState(
		int parallelism,
		int maxParallelism,
		int numberKeys,
		int numberElements,
		boolean terminateAfterEmission,
		int checkpointingInterval) {

	StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
	env.setParallelism(parallelism);
	if (0 < maxParallelism) {
		env.getConfig().setMaxParallelism(maxParallelism);
	}
	env.enableCheckpointing(checkpointingInterval);
	env.setRestartStrategy(RestartStrategies.noRestart());
	env.getConfig().setUseSnapshotCompression(true);

	DataStream<Integer> input = env.addSource(new SubtaskIndexSource(
			numberKeys,
			numberElements,
			terminateAfterEmission))
			.keyBy(new KeySelector<Integer, Integer>() {
				private static final long serialVersionUID = -7952298871120320940L;

				@Override
				public Integer getKey(Integer value) throws Exception {
					return value;
				}
			});

	SubtaskIndexFlatMapper.workCompletedLatch = new CountDownLatch(numberKeys);

	DataStream<Tuple2<Integer, Integer>> result = input.flatMap(new SubtaskIndexFlatMapper(numberElements));

	result.addSink(new CollectionSink<Tuple2<Integer, Integer>>());

	return env.getStreamGraph().getJobGraph();
}
 

@Test
public void testKeyedState() throws Exception {
	StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
	env.setParallelism(1);

	TestListResultSink<Long> resultSink = new TestListResultSink<>();

	DataStream<Long> source1 = env.fromElements(0L, 3L);
	DataStream<Long> source2 = env.fromElements(13L, 16L);
	DataStream<Long> source3 = env.fromElements(101L, 104L);

	KeyedMultipleInputTransformation<Long> transform = new KeyedMultipleInputTransformation<>(
		"My Operator",
		new KeyedSumMultipleInputOperatorFactory(),
		BasicTypeInfo.LONG_TYPE_INFO,
		1,
		BasicTypeInfo.LONG_TYPE_INFO);
	KeySelector<Long, Long> keySelector = (KeySelector<Long, Long>) value -> value % 3;

	env.addOperator(transform
		.addInput(source1.getTransformation(), keySelector)
		.addInput(source2.getTransformation(), keySelector)
		.addInput(source3.getTransformation(), keySelector));

	new MultipleConnectedStreams(env)
		.transform(transform)
		.addSink(resultSink);

	env.execute();

	List<Long> result = resultSink.getResult();
	Collections.sort(result);
	assertThat(result, contains(0L, 3L, 13L, 13L + 16L, 101L, 101L + 104L));
}
 

public static <IN, OUT, KEY> List<OUT> createAndExecuteForKeyedStream(
			OneInputStreamOperator<IN, OUT> operator, List<IN> inputs,
			KeySelector<IN, KEY> keySelector, TypeInformation<KEY> keyType) throws Exception {

	OneInputStreamOperatorTestHarness<IN, OUT> testHarness =
			new KeyedOneInputStreamOperatorTestHarness<>(operator, keySelector, keyType);

	testHarness.setup();
	testHarness.open();

	operator.open();

	for (IN in: inputs) {
		testHarness.processElement(new StreamRecord<>(in));
	}

	testHarness.close();

	ConcurrentLinkedQueue<Object> output = testHarness.getOutput();

	List<OUT> result = new ArrayList<>();

	for (Object o : output) {
		if (o instanceof StreamRecord) {
			result.add((OUT) ((StreamRecord) o).getValue());
		}
	}

	return result;
}
 

@Test(expected = InvalidProgramException.class)
public void testSortPartitionWithKeySelector2() {
	final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
	DataSet<Tuple4<Integer, Long, CustomType, Long[]>> tupleDs = env.fromCollection(tupleWithCustomData, tupleWithCustomInfo);

	// must not work
	tupleDs.sortPartition(new KeySelector<Tuple4<Integer, Long, CustomType, Long[]>, Long[]>() {
		@Override
		public Long[] getKey(Tuple4<Integer, Long, CustomType, Long[]> value) throws Exception {
			return value.f3;
		}
	}, Order.ASCENDING);
}
 

public <K> void configureForKeyedStream(
		KeySelector<IN, K> keySelector,
		TypeInformation<K> keyType) {
	ClosureCleaner.clean(keySelector, ExecutionConfig.ClosureCleanerLevel.RECURSIVE, false);
	streamConfig.setStatePartitioner(0, keySelector);
	streamConfig.setStateKeySerializer(keyType.createSerializer(executionConfig));
}
 

@Test
public void testOpenClose() throws Exception {
	KeySelector<Integer, Integer> keySelector = new KeySelector<Integer, Integer>() {
		@Override
		public Integer getKey(Integer value) {
			return value;
		}
	};

	StreamGroupedFold<Integer, String, Integer> operator = new StreamGroupedFold<>(
			new TestOpenCloseFoldFunction(), "init");
	operator.setOutputType(BasicTypeInfo.STRING_TYPE_INFO, new ExecutionConfig());

	OneInputStreamOperatorTestHarness<Integer, String> testHarness =
			new KeyedOneInputStreamOperatorTestHarness<>(operator, keySelector, BasicTypeInfo.INT_TYPE_INFO);

	long initialTime = 0L;

	testHarness.open();

	testHarness.processElement(new StreamRecord<>(1, initialTime));
	testHarness.processElement(new StreamRecord<>(2, initialTime));

	testHarness.close();

	assertTrue("RichFunction methods where not called.", TestOpenCloseFoldFunction.closeCalled);
	assertTrue("Output contains no elements.", testHarness.getOutput().size() > 0);
}